In most cafeteria settings, there is a large window providing access to the dish room from the dining area. Positioned in this window are shelves where finished trays are set. The shelves are designed to carry the trays to the dish room. In most instances, the shelves are arranged on a conveyor comprised of a series of rotating carriers fastened to a concealed chain. Each carrier has tiers of individually removable shelves. Generally, the carriers and shelves are made of stainless steel. The side of the window-accessible to the customer/diner is designated the “drop-off” side, the opposite side of the window being inside the dish room. On the drop-off side, the customer places the used cafeteria tray onto a shelf, and on the dish room side, an operator removes the tray for cleaning.
Often, a customer will improperly load the tray onto a shelf, such that the front side of the tray extends beyond the allotted overhang (usually approximately 3 inches) of the shelf. In such a circumstance, the tray will contact the window frame, which may lead to equipment damage and, in some instances, injury to the customer. To prevent this problem from occurring, it is standard to utilize a safety mechanism adjacent the window frame side that the shelves move toward, as shown in FIGS. 1–3 and 7. The safety system usually comprises a photoelectric limit switch positioned at the top of the window in alignment with a reflector positioned at the bottom of the window. This simple detection system stops movement of the rotating shelves when a tray has been incorrectly placed thereon so that the tray does not collide with the window frame and fall off of the shelf or cause other trays to fall off of the shelves. Once the shelves have ceased movement, an operator must manually reposition the offending tray onto the shelf on which it sits.
While such a safety feature can prevent certain problems from occurring, it can be quite time consuming for an operator to leave the dish room every time a tray is misaligned on a shelf, which may lead to severe back-ups in the cleaning process, particularly at peak hours. Thus, it would be desirable to provide a device that would reposition a misaligned tray onto a shelf automatically to avoid intermittent system shut down and manual repositioning by an operator.